The inspection of eggs to assess their wholesomeness is an essential part of quality control. Modern egg handling and grading facilities have highly automated egg washing, weighing, grading and packaging equipment yet still depend to a large degree on human operators for the inspection and grading of the eggs. This operation is commonly referred to as candling.
The process of candling and the routing of eggs to selected lines for appropriate handling is well developed. Currently, operators visually identify faulty or flawed eggs in a moving stream of eggs passing through an inspection station, or candling booth, and with the aid of manual controls they notify the grading equipment to identify and route the eggs to the appropriate packing station.
By way of example, on a modern egg grading machine such as the "Diamond 8200" (Registered trade mark) automatic grader two operators view eggs as they are passed over high intensity lights while being slowly rotated. During this operation various faults or flaws are identified by the operators. Eggs that are "leakers" or broken pieces are removed by hand at the candling station. All others are either tagged or allowed to pass freely.
First quality (grade) eggs are allowed to flow directly to the main packing station, whilst defective or lesser grade eggs are allocated to one of up to four alternative packing stations. On the "Diamond 8200" grader, allocation of lesser grade eggs is performed within the candling booth using two wands, which are integrated with the grading machine control system. Each wand serves half the egg stream proceeding through the candling booth and is equipped with a finger grip at one end containing two buttons with a third button or "tip" located at its other extremity. To activate the wand, the "tip" is touched onto the surface of the egg to be graded by the operator. This action indicates a fault and when used in conjunction with the other two buttons, four categories can be identified. Similar systems of fault identification are used with other makes of automatic grading machines.
The disadvantages of current manual egg candling systems include:
(a) A full capacity system requires at least two highly skilled operators at any one time. PA0 (b) Operators must be vigilant at all times; with flow rates in excess of 45000 eggs/hour the operators experience high levels of fatigue and occupational stress. PA0 (c) Lack of attention or misjudgment allows undergrade eggs to pass, resulting in poor quality eggs reaching the marketplace. Often operators over-compensate and tend to "overpull" by routing first quality eggs to lesser grades, with consequential economic loss to the producer.